DESCRIPTION: This is a proposal to analyze rho-dependent signaling pathways. The main feature of this proposal involves the use of a novel delivery system utilizing Sindbis-virus based vectors. This will permit co-expression of several C3-resistant rho isoforms (and modifications thereof) in conjunction with the specific inhibitor of rho, the C3 exoenzyme, which will inactivate endogenous rho activity. It is argued that this is a more efficient mechanism of delivery than other procedures. Using this approach the investigator will determine if there are any differences in function of rho A, B and C. Mutational analysis will be used to identify potential regions in the C-terminus controlling subcellular localization and regions within the effector domain required for rho dependent cellular functions. Finally, the mutants will be used to identify potential downstream effectors or signaling partners of rho. This will include attempts to identify and characterize binding partners.